Do follow still helps, but may not pass PR. Do follow is nothing more than googles trick to try to get people to play by their rules. Do your own experiment. Build a bunch of 'no follow' links and watch your serps. goog does follow them, in fact, pretty much anything you put on the web gets followed by goog even things you don't want them to index. Try putting up a page you don't want goog to index, and only one 'no follow' link pointing to that page. Theoretically it should never be indexed. Watch it get indexed. Related links help, no matter if they are 'do follow' or not. The goog devours anything it can find and puts it into its server farm.
It makes sense. I have actually a directory of a project I did for a client's website, and i place a no-follow and still it was listed by google..
I know you are trying to help fellow DP members by giving high PR blog to comment on. But, commenting on high PR blogs with dofollow gives value in google's eye (search engine and PR). You can check dofollow using SearchStatus plugin or SeoQuake plugin that is installed in Firefox. Make sure to check the setting of this plugins to highlight/cross nofollow links in order to check it is nofollow. You can also, right click the link and check "properties". If you can see nofollow or external nofollow, than the link is nofollow. As for backlink checker, don't really rely on that. Most backlink checkers don't really gives accurate difference between dofollow and nofollow. You can try check your backlinks and site analysis at any of these 29 backlink checker.
...and even a nofollow link is a link, search engines follow them and people do too. and the main point of blog comments is not gaining backlinks, it's about discussions, something so many seem to forget these days. and contributing to the discussion and addind value to the original post will get you direct traffic, just like Lastbutnotleast said there.